Handbook for Methane Control in Mining - AMMSA

183NNatural ventilation, coal silos ................................145Numerical simulation, methane reservoirs ............122OOil shale mines ......................................................153Origins of coalbed methane.....................................77Outbursts................................................................107Oxygen deficiency...................................................66PPaleochannels ..........................................................98Petroleum mines ....................................................154Pipelines in mines....................................................90Placement of sensing heads, methane monitors.......32Portable methane detectors................................27–28Potash mines..........................................................154Prediction of gas emissions ...................................119Pressure, effect on explosibility.................................5Production decline analysis, degas boreholes........118RRaise bore drills, ventilation of..............................130Recirculation, hazards of .........................................14district.................................................................16dust scrubber.......................................................15in headings..........................................................15Reserve ventilating capacity, bleeders.....................68Reservoir engineering methods .............114, 117–118Reservoir modeling........................................122–123Reservoir properties, coal seams .............................78Restricted spaces, sampling in.................................30Rock dusting requirements ....................................148SSample draw systems in methane detectors.............13Sampling accessible spaces for methane .................29Sampling restricted spaces for methane.............30–31Sandstone channels..................................................98Scrubber clogging, continuous miners.....................44Scrubber exhaust direction, continuous miners...44–45Scrubbers, continuous miners............................41, 45Sealing pillared areas...............................................69Seasonal trend in explosions....................................19Sedimentary intrusions ..........................................104Separate mine fans, effect on bleeders.....................73Setback, brattice, continuous miners .......................39Shafts.............................................................127–134barometric pressure...........................................133cutting and welding ..........................................129filling, at closed mines......................................132restricted spaces........................................129–130sampling guidelines ..........................................128ventilation guidelines........................................127water rings ........................................................129work decks........................................................128Shearer-clearer, longwalls .......................................56Silos – See Coal silos ............................................141Specific methane emission ......................................80Splits of air, bleeders ...............................................73Spray fan system, continuous miners ......................40Sprays, longwall ................................................56, 58Startup and recovery ventilation, bleeders...............74Static electricity .........................................................8TTemperature, effect on explosibility..........................5Thresholds for coal seam degasification..................80Trona mines...........................................................154Tunnels ..........................................................169–180assessing the hazard..................................169–171auxiliary ventilation..........................................175blowing ventilation ..........................................173checking the ventilation system........................177cumulative ventilation inefficiencies ................176dilution of methane to safe levels .....................171early indicators of a gas problem......................169exhaust ventilation............................................173face ventilation effectiveness............................173face ventilation systems....................................172fixed-site methane monitors .............................178gas checks.........................................................177handheld methane detectors..............................178human factors ...................................................179ignition sources.................................................179inadequate overlap in auxiliary systems ...........175lower explosive limit ........................................171main ventilation systems...................................172monitoring for methane ....................................177multiple preventive actions...............................172overlap in auxiliary systems .............................175planning ............................................................169potentially gassy ...............................................179recirculation......................................................175shutdown test ....................................................178stagnant zones...................................................174upper explosive limit ........................................171ventilation efficiency ........................................176